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Memristor initial-boosted coexisting plane bifurcations and its extreme multi-stability reconstitution in two-memristor-based dynamical system

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Science China(technological Sciences) 2020年第4期63卷 603-613页

作者： BAO Han CHEN Mo wu HuaGan BAO BoCheng School of Information Science and Engineering Changzhou UniversityChangzhou 213164China

Initial-dependent extreme multi-stability and offset-boosted coexisting attractors have been significantly concerned *** paper constructs a novel five-dimensional(5-d)two-memristor-based dynamical system by introducing two memristors with cosine memductance into a three-dimensional(3-d)linear autonomous dissipative *** theoretical analyses and numerical plots,the memristor initial-boosted coexisting plane bifurcations are found and the memristor initial-dependent extreme multi-stability is revealed in such a two-memristor-based dynamical system with plane ***,a dimensionality reduction model with the determined equilibrium is established via an integral transformation method,upon which the memristor initial-dependent extreme multi-stability is reconstituted theoretically and expounded ***,physically circuit-implemented PSIM(power simulation)simulations are carried out to validate the plane offset-boosted coexisting behaviors.

关键词： memristor-based system memristor initial coexisting plane bifurcations extreme multi-stability

Exploiting user behavior learning for personalized trajectory recommendations

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Frontiers of Computer Science 2022年第3期16卷 141-152页

作者： Xiao PAN Lei wu Fenjie LONG Ang MA School of Economics and Management Shijiazhuang Tiedao UniversityShijiazhuang 050043China

With increasing popularity of mobile devices and flourish of social networks,a large number of trajectory data is *** data contains a wealth of information,including spatiality,time series,and other external descriptive attributes(i.e.,travelling mode,activities,etc.).trajectory recommendation is especially important to users for finding the routes meeting the user’s travel needs *** existing trajectory recommendation works return the same route to different users given an origin and a ***,the users’behavior preferences can be learned from users’historical multi-attributes *** this paper,we propose two novel personalized trajectory recommendation methods,i.e.,user behavior probability learning based on matrix decomposition and user behavior probability learning based on Kernel density *** transform the route recommendation problem to a shortest path problem employing Bayesian probability *** the user input(i.e.,an origin and a destination),the trajectory query is performed on a behavior graph based on the learned behavior probability ***,a series of experiments on two real datasets validate the effectiveness of our proposed methods.

关键词： trajectory recommendation big trajectory data trajectory computing geo-social networks

Synthesis of mesoporous core-shell structured GdPO4:Eu@SiO2@mSiO2 nanorods for drug delivery and cell imaging applications

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Journal of Rare Earths 2020年第10期38卷 1086-1092页

作者： Yanli wu Xianzhu Xu Xiuli You Qiang Xiao Jiangxi Key Laboratory of Organic Chemistry Jiangxi Science and Technology Normal University College of Life Science Jiangxi Normal University

Mesoporous GdPO:Eu@SiO@mSiOcore-shell nanorods(NRs) were prepared by a facile two-step ***,the monodispersed GdPO:Eu NRs were obtained on a large scale via a facile precipitation method,then mesoporous silica was wrapped onto their surface through hydrolysis of tetraethylorthosilicate(tEOS).the XRd result indicates that the as-prepared GdPO:Eu NRs core has hexagonal *** FtIR and the Nadsorption/desorption isotherm analysis confirm the successful coating of mesoporous *** tEM images show that the obtained GdPO:Eu@SiO@mSiONRs exhibit uniform monodisperse core-shell structure with a nanorod core(length of 200 nm;width of 20 nm),and mesoporous silica shell of 15 *** excitation of 274 nm,GdPO:Eu@SiO@mSiONRs show strong red luminescence from ~5 d→~7 F(J=1,2,3 and 4) transitions of ***,the GdPO:Eu@-SiO@mSiONRs exhibit obvious tenhancement effect due to paramagnetism of *** drug loading capacity and pH-sensitive releasing behavior of the as-prepared GdPO:Eu@SiO@mSiONRs were studied by using doxorubicin(dOX) as model *** excellent biocompatibility of GdPO:Eu@-SiO@mSiONRs was demonstrated by Mtt *** together,the mesoporous GdPO:Eu@-SiO@mSiONRs may be potentially applied in fields of drug delivery and dual-modal imaging.

关键词： Core-shell structure Mesoporous silica drug delivery Optical imaging Magnetic resonance imaging Rare earths

A New theoretical Framework of Pyramid Markov Processes for Blockchain Selfish Mining

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Journal of Systems Science and Systems Engineering 2021年第6期30卷 667-711页

作者： Quanlin Li Yanxia Chang Xiaole wu Guoqing Zhang School of Economics and Management Beijing University of TechnologyBeijing 100124China School of Management Fudan UniversityShanghai 200433China department of Mechanical Automotive&Materials EngineeringUniversity of WindsorWindsorOntarioCanada

In this paper,we provide a new theoretical framework of pyramid Markov processes to solve some open and fundamental problems of blockchain selfish mining under a rigorous mathematical *** first describe a more general model of blockchain selfish mining with both a two-block leading competitive criterion and a new economic incentive *** we establish a pyramid Markov process and show that it is irreducible and positive recurrent,and its stationary probability vector is matrix-geometric with an explicitly representable rate ***,we use the stationary probability vector to study the influence of orphan blocks on the waste of computing ***,we set up a pyramid Markov reward process to investigate the long-run average mining profits of the honest and dishonest mining pools,*** a by-product,we build one-dimensional Markov reward processes and provide some new interesting interpretation on the Markov chain and the revenue analysis reported in the seminal work by Eyal and Sirer(2014).Note that the pyramid Markov(reward)processes can open up a new avenue in the study of blockchain selfish *** we hope that the methodology and results developed in this paper shed light on the blockchain selfish mining such that a series of promising research can be developed potentially.

关键词： Blockchain Proof of Work selfish mining main chain pyramid Markov process pyramid Markov reward process phase-type distribution Matrix-geometric solution

Injectable composite hydrogel based on carbon particles for photothermal therapy of bone tumor and bone regeneration

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Journal of Materials Science & technology 2022年第23期118卷 64-72页

作者： Chengxiong Wei Xin Jin Chengwei wu Wei Zhang State Key Laboratory of Structure Analysis for Industrial Equipment Department of Engineering MechanicsDalian University of TechnologyDalian 116024China

Surgical resection,as the most efficient treatment for bone tumor,still faces a dilemma between the complete removal of tumor tissue and the maximum reservation of healthy bone *** response to this,an injectable composite hydrogel with chitosan/hyaluronic acid/β-sodium glycerophosphate as the matrix and carbon particles as the photothermal agent is *** to the temperature sensitivity,the composite hydrogel can be injected into the irregular bone defect and exhibit the sol-gel phase transition upon body temperature,facilitating the conformal *** composite hydrogel can ablate the human osteosarcoma on Balb/c nude mice model with the tumor inhibition rate of 98.4%after near-infrared laser irradiation(808 nm).the assessment of bone regeneration on calvarial-defect model of Sprague-dawley rats reveals that the composite hydrogel can promote new bone formation with the bone volume/total volume ratio of 76.2%after 8 weeks,in sharp contrast to the control group of 23.9%.)

关键词： Hydrogel Carbon particle Photothermal therapy Bone regeneration

Mechanical Response of Conductor on Round Core(CORC)Cables Under Electromagnetic Force

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Acta Mechanica Solida Sinica 2023年第3期36卷 418-427页

作者： Junfeng wu donghui Liu Xingyi Zhang Huadong Yong Key Laboratory of Mechanics on disaster and Environment in Western China Ministry of Education of ChinaLanzhou UniversityLanzhou 730000China department of Mechanics and Engineering Sciences College of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China

the conductor on round core(CORC)cables are fabricated with multilayer high-temperature superconductor tapes,which are helically wound around a circular central *** large Lorentz force will be generated by the transport current in CORC cables under high magnetic field,which will affect the stress and strain distributions of tapes in the cables and the performance of superconducting *** paper establishes a two-dimensional axisymmetric model to analyze the mechanical response of CORC cables subjected to the Lorentz force and analyzes the influence of air gaps on stress and strain distributions inside the *** t-A method is used to calculate the distributions of current density,magnetic field and the Lorentz force in CORC *** mechanical response of CORC cables is analyzed by applying the Lorentz force as an external load in the mechanical *** direction of electromagnetic force is analyzed in CORC cables with and without shielding current,and the results show that the shielding current can lead to the concentration of electromagnetic *** maximum stress and strain occur on both sides of the superconducting tapes in the cables with shielding *** the size of air gaps can reduce the stress and strain in the superconducting *** analysis of mechanical response of CORC cables can play an important role in optimizing the design of CORC cables and improving transmission performance.

关键词： CORC cables Electromagnetic force Mechanical response Air gaps

Interlayer engineering in 3d graphene skeleton realizing tunable electronic properties at a highly controllable level for piezoresistive sensors

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Nano Research 2023年第7期16卷 8512-8521页

作者： Xunxiang Hu Lingling tan Xianzhang wu Jinqing Wang College of Material Science and Engineering Hunan Province Key Laboratory of Materials Surface&Interface Science and TechnologyCentral South University of Forestry and TechnologyChangsha 410004China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

three-dimensional(3d)graphene is a promising active component for various engineering fields,but its performance is limited by the hidebound electrical conductivity levels and hindered electrical *** we present a novel approach based on interlayer engineering,in which graphene oxide(GO)nanosheets are covalently functionalized with varied molecular lengths of diamine *** has led to the creation of an unprecedented class of 3d graphene with highly adjustable electronic *** calculations and experimental results demonstrate that ethylenediamine,with its small diameter acting as a molecular bridge for facilitating electron transport,has the potential to significantly improve the electrical conductivity of 3d *** contrast,butylene diamine,with its larger diameter,has a reverse effect due to the enlarged spacing of the graphene interlayers,resulting in conductive *** importantly,the moderate conductive level of 3d graphene can be achieved by combining the interlayer spacing expansion effect and theπ-electronic donor ability of aromatic *** resulting 3d graphene exhibits highly tunable electronic properties,which can be easily adjusted in a wide range of 2.56-6.61 S·cm^(-1)compared to pristine GO foam(4.20 S·cm^(-1)).this opens up new possibilities for its use as an active material in a piezoresistive sensor,as it offers remarkable monitoring abilities.

关键词： graphene tunable electronic properties multifunctional composites piezoresistive sensor

A 3-d numerical simulation of the characteristics of open channel flows with submerged rigid vegetation

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Journal of Hydrodynamics 2021年第4期33卷 833-843页

作者： Jun-tao Ren Xue-fei wu ting Zhang School of Environment and Resource Southwest University of Science and TechnologyMianyang621010China

this paper applies the Flow-3d to investigate the impacts of different flow discharge and vegetation scenarios on the flow velocity (including the longitudinal, transverse and vertical velocities). After the verification by using experimental measurements, a sensitivity analysis is conducted for the vegetation diameter, the vegetation height and the flow discharge. For the longitudinal velocity, the greatest impact on the flow structure originates from the vegetation diameter, rather than the discharge. the vegetation height, however, determines the inflection point of the vertical distribution. Comparing the transverse velocities at two positions in the vegetated area, i.e., the upstream and the downstream, a symmetric pattern is identified along the water depth. the same pattern is also observed for the vertical velocity regardless of the flow or vegetation scenario, including both transverse and vertical fluid circulation patterns in the vegetated area. Moreover, the larger the vegetation diameter is, the more evident these patterns become. the upper circulation occurs near the vegetation canopy. these findings regarding the circulations along the transverse and vertical directions in the vegetated region shed light on the 3-d flow structure through the submerged vegetation.

关键词： Submerged rigid vegetation longitudinal velocity transverse velocity vertical velocity open channel

Melting heat transfer enhancement of a horizontal latent heat storage unit by fern-fractal fins

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Chinese Journal of Chemical Engineering 2020年第11期28卷 2857-2871页

作者： Zilong deng Suchen wu Hao Xu Yongping Chen Key Laboratory of Energy thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow technology and Energy Application School of Environmental Science and EngineeringSuzhou University of Science and TechnologySuzhou 215009China

the latent heat storage(LHS)technique is of crucial importance in chemical energy *** by multi-bifurcated fern leaves,a mimic fern-fractal fin is designed to improve the thermal energy charging *** paper develops a transient melting model of a rectangular LHS unit using fern-fractal fins,and their melting behaviors are compared with the conventional ***,a parametric optimization of fernfractal fins is conducted for maximizing the thermal efficiency based on the response surface method(RSM).the results indicate that the temperature uniformity is more superior and the melting duration is shorter for the fern-fractal LHS unit when compared with the conventional ***,the fern-fractal LHS device presents a slower heat storage rate during the initial conduction-dominated and early convection-dominated melting stages,while a prominent melting enhancement is achieved during the later melting *** shortest melting time is obtained based on the RSM technique when a fern-fractal fin with length ratio α=0.94 and branch angle θ=54.7°is *** with a conventional fin,the averaged heat storage rate increases by 88.3%,and the total melting time is declined by 40.3%for an optimized fern-fractal fin.

关键词： Multiscale Fractal Numerical simulation Heat storage Optimization